What, exactly, can you do with a starship's augur arrays?

What is their range? Do they have an exact maximum range after which they are blind, or is there an optimal normal range followed by a range at which objects can be detected, but at less precision?

From how far away can a starship detect:

... a typically sized asteroid?

... a small transport sized ship?

... a cruiser?

... a ship of sub-warp capable size?

... the floating, frozen body of a Space Marine in stasis, adrift in only their power armour?

As an extension to the previous question, can one ship conceivably hide from another while both are in orbit of the same planet if both ships are of warp capable size? How about if the ship trying to hide is of sub-warp capable size?

Can a ship detect that another ship is about to enter (or has just entered) the warp? From how far away?

How much information can be acquired about another ship in sensor range? Can I, by means of my sensors, determine anything about how the ship is armed or outfitted? How much, and how easily? Can anything about potentially held cargo be determined, or the current crew quantities?

With what level of detail can information be acquired by directing a ship's sensors towards a planet? Can (and potentially from what distance could) a starship detect...

... whether the planet is basically inhabited?

... individual settlements of tribal (or urban) settlements on the planet's surface?

... individual large vehicles (such as landing craft/troop carriers)?

... interesting mineral or other resource deposits?

Can ship sensors achieve Google Earth style photos of arbitrary spots on the planet?

Oooooo Im sure a Mechanicus Lexfluff priest has just gone off to send a astropathic message to Mars to answer that one. My suspicion is that most of our instinctive tech tropes are taken from sci fi sources like starwars and startrek. Im sure that Imperial techcould do all that (and more-man reached his technological zenith millenia before) The main problem should be that knowledge is so debased that no-one really knows how it works any more or even configure it to optimum efficiency. I think that the problem is to do with time scale. In modern High tech universes captain Kirk or Obi Wan Kenobi flicks a switch and the information reels across the screen and BAM you know if the planet below is crawling with three legged critters. In the 40k universe it may be more of a case that the question gets asked to the officer who can operate a auspex relay, which gets sent down to a pannel of drooling hard wired servitors. Some incomprehensive babel then gets spouted out by one of the servitors. The auspex officer then has to translate it back to the rogue trader.

In game terms it probably means two things... a element of delay, and possible mistranslation. If you are willing to hang about for a week or so the engiseers could probably even configure the the auspex to figure out how many times the three legged critter goes to the toilet, but in a battle situation it should come across as painfully slow....

If however you want to be able to do these things the I suggest that knock up some tau xeno tech rules into your ship. The shiny high tech mangaesque levels of that the Tau use most closely resemble what we recognise and probably would explain away the ability to detect and process information at high speeds

What is their range? Do they have an exact maximum range after which they are blind, or is there an optimal normal range followed by a range at which objects can be detected, but at less precision?

I'd imagine the scanners of a starship to encompass a multitude of systems, each with their own range.

From how far away can a starship detect:

... a typically sized asteroid?

... a small transport sized ship?

... a cruiser?

... a ship of sub-warp capable size?

... the floating, frozen body of a Space Marine in stasis, adrift in only their power armour?

Generally, the distance is about 1p, with p defined as "the distance when it's convenient for the plot that they do".

As an extension to the previous question, can one ship conceivably hide from another while both are in orbit of the same planet if both ships are of warp capable size? How about if the ship trying to hide is of sub-warp capable size?

Hiding a starship sounds rather... improbable. Even if it's on the other side of the world, it's still huge and its plasma drives have some non-negligible energy output, although having a planet between you and the one you hide from does help (see page 213). A shuttle or guncutter is more possible.

Can a ship detect that another ship is about to enter (or has just entered) the warp? From how far away?

With active auguring, probably. You'd notice the Geller Field building up. Distance: 1p.

How much information can be acquired about another ship in sensor range? Can I, by means of my sensors, determine anything about how the ship is armed or outfitted? How much, and how easily? Can anything about potentially held cargo be determined, or the current crew quantities?

You can determine some of the ship's components when you're within combat distance with the Focused Augury action (see page 217).

With what level of detail can information be acquired by directing a ship's sensors towards a planet? Can (and potentially from what distance could) a starship detect...

... whether the planet is basically inhabited?

You could probably distinguish between four classes relatively easily: Uninhabitable, inhabitable with at least industrial revolution level civilization, inhabitable with at least space age civ.

... individual settlements of tribal (or urban) settlements on the planet's surface?

Tribal will be very hard if you're not just searching a relatively small area.

... individual large vehicles (such as landing craft/troop carriers)?

Possibly from low orbit, but only in a very small radius.

... interesting mineral or other resource deposits?

Probably with specialist augur systems.

Can ship sensors achieve Google Earth style photos of arbitrary spots on the planet?

As long as they're directly above said arbitrary spots (or have a satelite over it), possibly.

A lot of this comes down to how you see tech in 40k's Imperium. It tends to vary a lot ship to ship. One ship might have a complex holo display that shows the enemy ships in a lot of detail. Other ships have the Battle Star Galatica look with people reporting positions and moving models on a board. It's really up to you.

Things to consider:

-Space is really big if a ship isn't giving off a lot of energy, and isn't close by it's near impossible to detect without spending weeks doing active sensor sweeps. Detecting a body in space would require a ship nearly hit it unless the body had a beacon or something that reflected active sensors. That said if you knew where someone or something got thrown off a ship, and what the speed, time, and position of the ship was you could find a person sized object.

-Doing active sensor sweeps is a lot like waving a flash light around at night. A ship is going be able to detect another ship with active sensors long before the scanning ship sees them.

-In Battle Fleet Gothic (which FFG got most of their ship rules from) you can simplely disengauge by heading away from your foes and going dark. The ship rules in RT have an option to reduce power and sneak.

-A planet with a lot of tech is going to be obvious. Radios, lights at night, and the like. So unless they are paranoid all the time. IE night time blackouts, use tight beam microwaves, and laser they can't really hide. That said a small city would be very hard to find if it wasn't beaming radio communications all over.

-Entering and exiting the warp is pretty violent and a nearby ship's sensors would detect it. Psyker, astropaths, and navigators would detect it as well. That said a ship needs to emerge from warp pretty far outside the system. And this is a really really big area. Generally even in a well defended system an entire fleet can emerge from the warp, assemble, and start the several days trip in system before being detected. Astropaths, and Navigators seem alot better at detecting ships coming out of warp.

Dalnor Surloc said:

I agree with most of what you say, except the above about ship detection. Even if a ship is not using engines, weapons or active sensors it is still radiating massive amounts of thermal energy; space is not only big it is very, very cold and spaceships that have active life-support will be standing out like bonfires on a dark night. You cannot shield the radiation as any system to do so will require energy and that will show up very nicely too.

There is an excellent web-page [www.projectrho.com/rocket] that goes into the physics of space detection and the problems of hiding a ship in space. For instance it is calculated that the space shuttle's maneuvering thrusters can be seen from the orbit of Pluto, think what the thrusters on a RT ship would look like!

DW

Dalnor Surloc said:

On points one and three, i just have to add a couple of points of my own.

Space is indeed big and if a ship weren't giving off a lot of energy, it would be difficult to detect. However, active ships will be giving of a crap-ton of energy all the time and ships which have only recently become inactive (say within the past year) will still be radiating a lot of energy. This is due to two major aspects of 40k ships: they use plasma drives to get around (which burn at the heat of most suns, that's a crap-ton of heat) and they have thousands of people stuffed into them all radiating 98.6 degrees of heat each, keeping the ship nice and toasty. A 40k ship would have a hell of a lot of heat trapped within it that it would be slowly radiating for quite some time . All that heat amidst a whole lot of nothing would be fairly easy to detect. Now, if there was a lot of other things around the ship that were also fairly warm (more likely the closer to a systems sun the ship is) then it would become a lot harder to detect. So, a ship near the edges of a system would be a lot easer to pick up on then one hanging out close to the systems sun.

Reducing power on a ship I guess is a rather popular trope and I reckon there's some devices on a ship that came about during the DAoT to clamp down on the heat that the ships systems generated, but without some kind of technological wizardry that makes thermodynamics it's *****, a ship which completely cuts it's power will still have a lot of residual heat left over from when the plasma drives were on -it won't go away in an instant, never mind the thousands of folks who will still radiate 98.6 degrees of heat with only one way to turn them off.

Likewise, the fact that space is big is offset by the fact that space is exactly that, space. It's empty, it's nothing. Finding something amongst nothing isn't that hard. It only gets difficult if you're trying to find something amongst something. To go with the flashlight analogy, scanning space would be like shinning a flashlight around an empty featureless room that's been painted completely black. If there's a spaceship in that room, it would be like tossing a white sock into it. All you'd need to do is run your light over it for just a split second for you to know you've found something and, if you were looking for a white sock (or anything) you know you've probably found it. Finding that same sock in a cluttered room with piles of laundry about would be a lot more difficult and time consuming as you would have to identify each object you ran across enough to know whether it is the white sock or not.

So, basically, ships, on the whole, would be pretty damned easy in most situations to spot. The best way for them to hide is in areas that have a lot of other stuff, optimally close to the systems star.

Of course, that assumes that 40k uses the same space we do, which it very well might not. After all, if a ship can hide by "going dark" and since, in RT pg 261, space is said to be extremely cold, taking less then a minute for a body to freeze in it's cold unnamed void substance, then 40k space could very well be filled with ether. It is the retro-cool thing to do to space and 40k is up to it's knickers in cool and retro. ;-)

Edit: ya, what Dalnor beat me to saying... Well, kind of except our space isn't cold, it's not anything at all. In order for it to be cold, it would need to be something. Space isn't something, it's nothing. It can't be cold because there's nothing there to be cold. When we say "it's cold outside" what we're really saying is "the air outside is cold." There's no air in space, there's nothing. Space is exactly that, space between somethings.

However, it kind of depends on what sort of sensors/scanners they have. They might not be heat based, since their own drives, etc, could possibly interfere with any heat-based sensors. If they were more like sonar/radar, then it's more likely that a ship would be missed, because a "dark" ship would have less parts/crew moving around, and so possibly be harder to detect.

A couple of points:

1)Space is only mostly empty. In our own system there are at least 6,244 NEO (Near Earth Objects). It's taken us over a decade of searching and we aren't done yet. That only counts the objects that come close to the earth. The asteroid belt contains millions of object of various sizes plus an unknown number really small objects. Then you have the Oort Cloud with it's few trillion comet nuclei. It's more like a flashlight spinning in a stadium with a 10 thousand objects base balls, ball bearings, and a lot of dust....

2)Heat radiated by the plasma drives would only be radiated towards the rear of the ship. The front of the ship would only be radiating a little heat. There is a hell of a lot of infra-red sources in space (stars, planets...). Each source would need to be examined to determine where it came from.

Don't forget that enev though space is really big, it is also really full. Inside of a solar system there is an average of 1 marble-golf ball sized object every 30-100 km, depending on where in the system you are, and every 20-50,000 km squared has something up to the size of a soccer ball. That means there are roughly 1-3 million golfball size objects and about 200 to 500 larger objects in every square of RT ship scale movement. All of which are reflecting radiation and screwing up with sensor sweeps. The only places relatively free of these objects are close to a planetary orbit, within about 10 r of the planet itself. On top of that, if a ship is more that a few squares away, even spewing plasma and using active sensors, it is only putting out about as much energy as a background star is.

Trying to find an object in space is HARD, even if it is trying to be found. I worked with one of my profs trying to discover NEO's a few years back when I was an undergrad (To be fair, I was getting them coffee and every once in a while I was rewarded with getting to look at a few plates) and we often couldn't find objects even when we knew where they were. Without a dedicated system wide sensor net, it is quite feasible for a ship to pass within a hundred thousand km of another starship and never even know it was there.

the average NEO is under a meter. Most satelites under 3m. (Actually, the tracking is for objects 2cm+... most of which can't be detected from surface except with radar, since their light is scattered all to heck by the atmosphere)... Ships in 40K are the size of small asteroids, 500x400x1500m being "small", and 200+ degrees warmer, generally...

Most asteroids are detected with small scopes (5" to 10"). It's mostly a matter of processing power and having divergent points of view (physically), and then ruling out known objects.

Thing is, a moving ship has an easier time of object detection than any planetbound observer, since the point of view changes much faster. It's the difference of position vs the background field (which changes VERY slowly with motion), using a comparator.

Detecting ships should be pretty simple, assuming one has Passive IR and a good scope, but it takes time. 3-4 images 3-4 min apart when moving 1,000kmh should detect anything bright enough to show. If they are under thrust, they should show up like a torch on IR. 2000°K plasma will show up rather instantly that way, against a 3°K background.

First, we can only track objects of that size due to the fact that earth has already swept nearly everything out of it's orbit. And even then it is really dame hard to find even the larger ones. And the thing the empire lacks is processing power. I doubt they have the processing power to reliably view a .1 arc photograph, much less the 10 degrees they'd need to scan with any speed.

1,000 kpk is nearly a dead stop for ships in 40k. the slowest military ship in BFG, the Emperor Class Battleship, as well as ships like transports, have a cruising speed nearly two orders of magnitude higher than that. In order to slow down and take those pictures the ship would need to spend nearly an hour slowing down, stay still four hours taking pictures in every direction, and then, assuming there was anything to find, start back up again. Not to mention that a ship with a crusing speed of 60,000 kph at a range of 100,000 km will have moved over 6 degrees out of position in those four minutes between shots. 100,000 km is well within 40k scanning range, I am just trying to make a point that I know form experance that scanning in space is harder than most poeple think. If it seems otherwise I blame it on the vikoden. And due to the myriad of factors that can go wrong, I could easaly see how a powered down ship can stay hidden at ranges of 100,000 km+.

I hope this all makes sense. I am recovering from my wisdom teeth out on vikoden.

Digging through the rules... the sensor kits can detect down-powered ships to 20VU; that is, about 200000km, 200 million meters, 2/3 of a light second. (p214, Disengage) Inactive ships are automatically detected on a successful active scan out to same range, +5 per VU.

Active ships in that range and beyond are automatically detected by passive sensors.

how far beyond 20 VU can ships be detected?

It's not clear from the rules. So here are some assumptions based upon reasonable rules extrapolations. (note: these ranges are well under the Traveller T4 Definitive Sensor Rules ranges for similar sized vessels, written by a working Astronomer, and generally consistent with NASA published detection capabilities.)

We can reasonably assume anything close enough to affect the battle is automatically DETECTED by passives at a range greater than (max ship speed x 8) + (weapon range x2) -4... which means (10 x8)+(9x2)-4 = 84 vu... because this gives 1 turn maneuver and 1 turn to engage, assuming both were on a converging course to begin with. I'd round that up to a convenient 100VU, myself (which is 5x the detection range of downpowered ships with active auspex). That's 3.3LS... two-and-a-half times the distance to the moon and a touch.
Why x8?
max allowed push is 1 less than 2x base speed. Which would require really awesome rolls, but it's possible to push a speed 10 to speed 19 (it's even reasonably likely with combined Flank Speed and Adjust Speed. So we allow for the maximum possible movement ((2 turns x (2xSpeed-1)) x 2 ships), apply the distributive property, 2x2x2xspeed +2x2x(–1) =(8x speed) –4, then add the maximum range of weapon (2x listed range)...

Now, counting Automatic at +40, -10 per full 100 AU, I'd allow a passives roll to detect active ships past 100 AU, so 200AU is +30, 300 is +20, etc, out to 800VU (-30), since the next step after a -30 base difficulty is autofail... Which gives a chance out to 26.666 LS...

Note that, at maximum speed, 20vu/T, that's 20T minimum closing time.... longer if not on closing course.

There are other elements to consider. Detecting radiating bodies in deep space is not nessecarily a trivial feat (certainly not at the level of star trek): Just ask any radio astronomer. There is a bit of luck involved. For one thing, you are looking at a very narrow arc for objects further than a few hundred million kilometers away. Even a starship would look like the eye of a needle as viewed from the opposite end of a football field.

There are other things to consider as well. For example relative speed and its effect of radiatiing bodies. If we're talking about heat in space, then what we're really talking about is a certain set of EM freq's we refer to as infa-red. If the scanning vessel had some idea of its own velocity relative to the ship its tracking, then it could narrow its search. However, if the ship were moving at high reltive velocity in relation to a cool radiating body, then that body would appear quite a bit hotter than it actually is. If the scanners were moving at a high relative velocity away from, say, a retreating ship, then the retreating ship would appear to be a lot colder than it actually is -at at long range, the amplitude of the EM coming off of the vessel would decrease too. A retreating ship on full burn, at sufficient distance could well appear as an infra-radio signal, depending on the distances and speeds involved. A ship retreating with systems cold could practically vanish into the dark (if moving fast enough)

The saving grace would be patterned transmission which could be parsed out of a wider set of signals by computer programs. Radio traffic might be reasonably easy to find with enough antennea and supercomputers working on the task, but that's assuming all the antennae are pointed in the right direction, and assuming the object is broadcasting patterned signals (active sensor sweeps, radio transmissions, etc).

Which raises another issue, Higher freq em-signals much be searched for with increasingly directional sensors. A big fat dish is sufficient for detecting radio-traffic, but a directional telescope is more appropriate for light in the visual spectrum, and so on for higher and higher freq's. So I suppose another question would be. where do you point your sensors to begin with?

There is also the speed of light, which would indicate at 149000000 kilometers (earth to sun) not where a vessel is, but where it was eight minutes ago, and using ir or radio-waves, you wouldn't even necesarily get a precise read on that immediately.

In short, Starship combat would probably play out a bit like submarine combat. To ships in the void, at 100000000 kilometers away from eachother, are very much in the dark. Whoever detects their foe first, would have a tremendous advantage.

There are factors to be taken into consideration also when talking about the use of sensors trying to gather information on planets and in the use of hiding/attacking other ships. First regarding the whole Star Wars/ Star Trek debate. I think there's a bit of misunderstanding here as to the capabilities of their sensors. I think in Star Wars it was best shown in Empire when Luke did a flyover of Dagobah and found "lots of life but no discernible settlements" in other words he had no way of knowing if there was any kind of intelligent life down there. The simple fact of their sensors in both cases is they simply looked in the case of planets they hadn't been to before. Especially on Star Trek you always saw the bridge of the Enterprise having great magnification on visual sensors. It's not that hard to actually see civilizations on a planet. For example on this planet alone the great wall and the light at the top of the Luxor in Las Vegas can both be seen clearly from space. As to further detecting civilizations and how advanced they are, just do a wide spectrum radio sweep to see if there's any kind of communications and that will give you some kind of idea of the tech level involved. If you pay close attention to Star Wars and Star Trek though the big secret is most of the planets they get information on are ones that someone had been to before. For example, Han Solo in Empire scanning nearby systems for a good place to hide found out that Lando was the administrator on Bespin. Finding life isn't that hard and determining civilization equally not that hard. To the point of detecting millitary/tech capabilities that would come down to how hard the people try to hide it. In the U.S. a lot of our military capability are parked in places that are fairly easy to see. Planes are often kept parked outside their hangars, tanks and vehicles parked in parking lots and it's impossible to hide a ship that isn't at sea. Once again it all comes down to what you can easily see. Conversely if an advanced civilization had something hidden below the planet's surface or such and no one is talking about it it would be next to impossible to find.

In the case of detecting ships, sure the sensors can detect ships easily but there are other factors that should be taken into consideration. In any case of sensors regardless of the type if a ship can find a large enough body to hide behind the sensors will not be able to see them, they will see the object they are hiding behind instead. In the case of radar ships can hide their numbers if they are in a fleet by clustering close together. The radar will only read one large blip instead of the cluster of small ones (in modern equivalent it's like a flock of birds appearing as one blip). Also if a ship hides behind a larger item such as an asteroid or planet the sweeping sensors will pick up the planet not the ship. If the ship is running dark then that will increase the unlikelihood of being detected as the object's own radiations will throw off other sensors and even if the sensors worked on an ir principle the density of the celestial object will throw off the sensors. (IR sensors can't read through vault walls, how would they read through a planet or asteroid.

Just some food for thought

Another thing to consider: Radiotelescopes are often focused to under 1 degree field of view (typically 30'-40'... 0.5-0°.666°). Optical often down to a undr a minute; Hubble is 52x52 arc-seconds (0.01444°). A short but wide angle scope can be easily constructed with 15°x15° fields of view... 288 shots to complete survey (360°x180°), instead of the 310579882 Hubble would require. Different applications, different design. Detection scopes will probably be short focal length wide angle reflectors, and on a ship as big as a even a small transport in RT, these 1m instruments can be fixed mounts with dedicated crewmen!

Some optical scopes have fields of view under an arc second.

here's a toy to play with on that score: www.csgnetwork.com/telefov.html

Pretty much, you can only make use of a 90° apparent field of view, and 45° is easier. Still, short focal length, and possibly stereo scopes... pretty trivial, especially since they will be brighter than pluto is, just due to the engines.

Only one point to make, you can't actually see the Great Wall from space, that's a myth. In the 60's the Chinese put that info out as a great piece of propaganda, and people believed it. The US went along with this to imply it's spy capability was better than it actually was and hide the fact they hadn't spotted it. When they actually got there it was expedient for a while to propagate the myth, until it entered into urban legend, but you can't see the Great Wall from space (with the naked eye).